Insulator



Sept. 29, 1931. G. M. BARROW INSULATOR Filed March 7, 1927 INVENTOR George A1 B0 rrow.

AT'IFORNEY Patented Sept. 29, 1931 UNITED STATES PATENT OFFICE GEORGE M. BARROW, OF DERBY, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA INSULATOR Application filed March 7, 1927. Serial No. 173,863.

My invention relates to insulators and particularly to insulators of the pin type.

One object of my invention is to provide an insulator, of the above-indicated character that shall materially reduce losses in manufacture.

Another object of my invention is to provide an insulator that shall render more perfeet certain parts which have heretofore been unreliable in character.

A further object of my invention is to provide an insulator that shall be simple and desirable in construction, economical to manufacture and effective in its operation.

In the manufacture of porcelain insulators of the pin type, it has heretofore been usual to form the screw threads in the pin holes thereof by a reversing machine, either during or after the pressing operation which forms '20 the insulator proper, while the porcelain batch is in a plastic state. This operation usually requires the use of a relatively complicated and expensive machine. However, aside from the complication of the machine, 95 the forming of the screw threads directly in the main insulating body has the further objection that the threads frequently warp out of shape, during the firing of the insulator, so that relatively great losses occur in manufacture.

Warping of the threads is assisted by the firing of adjacent integral portions of different thickness or cross-sections, since the smaller or thinner sections tend to dry out first and to leave a deleterious effect which is not so pronounced in portions of uniform or similar thickness.

In practicing my invention, I provide an insulator and a method of making the same, whereby the screw threads, or similar holding portions, are formed separately from, or independently of, the main insulator body to eliminate the use of the above-mentioned reversing machine during manufacture and to provide an insulator structure in which the above-mentioned objections are not present.

Figure 1 of the accompanying drawings is a side view, in longitudinal central section, of an insulator constructed in accordance with 150 my invention, and

Fig. 2 is a detail view of a modified portion thereof.

The insulator comprises, in general, an upper insulating member 2, a lower insulating member 3 having a recess 4 for the reception of a pin or similar member for association with the insulator, and a holding element or sleeve 6 for cooperation with the pin.

The upper insulating member 2 comprises a surface-creepage petticoat 7, a tie-wire groovev8, a groove 10 for the reception of a conductor to be supported by the insulator and a portion 11 of inverted substantially cup-shape that is cemented, or otherwise secured, to a head portion 12 of the lower insulating member 3. The member 3 further comprises surface-creepage petticoats 14 and 15. i

The above-described structure is merely illustrative of an insulator for which 111 invention is adapted, since the upper member 2 may be an integral part of the member 3 or the device may comprise three or more parts similar to the parts 2 and 3. The sleeve 6, which has usually heretofore been constructed as an integral or homogeneous part of the member 3, is, according to my invention, formed separately therefrom, either by a wet process or by a dry process, and secured in the member 3 in any one of several ways. i

A preferred method of making the sleeve 6 is by the dry process in which the sleeve may be made single and homogeneous or in longitudinally divided half sections 17 and 18. The latter method has the advantage of rendering the operation a simple pressing operation and to render a reversing mold unnecessary. Such a reversing mold, or other relatively complicated and expensive means, is required. where screw threads 20 are desired in the sleeve 6 and it is also desired to have the sleeve consist of one integral 'member. By longitudinally dividing the sleeve 6, it may be withdrawn laterally from the mold and placed together again for insertion in the recess 4.

The sleeve 6 may be formed as a thimble,' having its inner end 21 closed instead of open, as shown in Fig. 2. While the sleeve 6' may be secured in position to advantage V 40. effected therein Without departing from the by the use of metal alloy, molding composition'o'r frangiblecement,it is preferably insulatinglybonded to the member 3 by a frangible or refractory material, such as glaze or porcelain slip. In any case, the adjacent surfaces of the sleeve 6 and member 3 may be roughened, grooved, sa11ded or gtherwise treated to ensure a more perfect 'Where'p0rcelain slipor glaze is-used. as

thebonding material, the member 3fand the. sleeve 6 may be fired before the assembly thereof with the slip or glaze and again fired to vitrify the bonding material or, all of the parts may be united before firing.

Since it is my main purpose to provide a refractory insulator having a refractory thread inthe pin recess similar to, but more perfect than,"insulators of this typeheretofore employ'ed and to retain certain other characteristics of the single homogeneous unit, the sleeve 6 ispreferably unitedto the 7 recess.

I 2'. An insulator comprisingan insulating member having a pin recess and alongitudinally-divided"insulating sleevesecured in positionin said'recessfor holding 'co-operat'ion with. a pin removably associated with member 3 by glaze or slip. By this method, an insulator is provided that, While made up of separately fabricated parts, is substantially as homogeneous from an insulating standpoint andhas more perfect threads than the prior art structures. By firing the member 3 and the-sleeve 6 separately, orby preforming them and assembling the same with glaze'or slip therebetween before firing,

warping of the sleeve is less likely to occur a r and losses from thiscause are accordingly materially reduced. 7 V

' Also, by employing the dry-press process and longitudinally dividing the sleeve or thimble, a reversing mold is dispensed with and more perfect threads are ensured,

VVhi'le I have shown and described particular forms of my invention, changes may be spirit'and scope'thereof, asset forthin the appended claims. V

V Ielaim as my invention: p

' 1. An insulator comprising 7 a' recessed insulating, member and a longitudinally divided internally scr'ew-threaded insulating sleeve constituting a relatively thin lining fortand compared to the thickness of the side Walls thereof and bonded thereto in said the insulator in said recess.

3. An insulator comprising a recessed in sulating member and a longitudinally di vided 'internallykscrew-threaded element having a sleeve and a transverse wall constituting relatively thin linings bonded to the insulator insaid recess. l

{.L. Ar -insulator comprising aninsulating memberhaving a pin recess and a longitudi v 

